The present disclosure relates to an electrolyte membrane, a fuel cell, and an electrolyte membrane manufacturing method. More specifically, the present disclosure relates to an electrolyte membrane that can be used in a fuel cell that operates under medium temperature, non-humidified conditions, a fuel cell that uses the electrolyte membrane, and an electrolyte membrane manufacturing method.
Recently, the development of a medium temperature dry fuel cell (MTDFC) that operates in a medium temperature region of 100° C. to 250° C. under conditions of low humidification or no humidification has been anticipated. The MTDFC can simplify a fuel reformer. Moreover, the MTDFC does not require a humidifier. The MTDFC can also improve the energy utilization rate by utilizing exhaust heat. Out of consideration for the environment, the MTDFC is required to use an electrolyte membrane with a basic structure of an aromatic hydrocarbon that does not contain fluorine.
An electrolyte membrane with a basic structure of polybenzimidazole (PBI) has been proposed as an electrolyte membrane with a basic structure of an aromatic hydrocarbon that does not contain fluorine (for example, refer to Patent Document 1). The electrolyte membrane contains PBI, an inorganic acid, and adenylic acid. The energy utilization rate of the electrolyte membrane can be improved by raising its phosphoric acid doping ratio to increase its conductivity.